Southern California air-quality regulators are sponsoring an in-depth study to determine if the San Bernardino Rail Yard, a major inland hub of goods shipped across the U.S., has caused an increase in cancer and asthma in the neighboring low-income communities. The study comes two years after the California Air Resources Board determined that diesel emissions from locomotives, big-rigs and other equipment at the facility posed a significant health risk to thousands of residents living near the site, and that the facility posed the greatest cancer risk of any rail yard in California.

Asthma pills appear to work just as well as inhaled steroids at relieving asthma symptoms in real-life settings, researchers have found, apparently because people prefer swallowing a pill to sticking something up their nose. In one clinical trial, asthma sufferers who took as a first-line therapy the oral medications Singulair or Accolate , each a brand of leukotriene-receptor antagonists, reported as much symptom relief on a quality-of-life survey at two months as those who used an inhaled glucocorticoid, according to a new study published in the New England Journal of Medicine.

The rise in asthma rates has researchers a bit baffled. But while they focus on figuring out the reason, people with asthma have more practical concerns: preventing and controlling asthma attacks. Data released Tuesday from the Centers for Disease Control and Prevention show an increase in the number of Americans with asthma despite better air quality and a marked decline in smoking rates, as reported in the Los Angeles Times . Doctors don't know how to prevent asthma because it's not clear what causes the disease - it may be caused partly by genetics and partly by exposure to irritants such as pollution and tobacco smoke.

About one in 12 people in the United States now has asthma, a total of 24.6 million people and an increase of 4.3 million since 2001, the Centers for Disease Control and Prevention said Tuesday. The costs of medical care for these patients increased by about 6% between 2002 and 2007, totaling $56 billion in the latter year, according to information in the CDC's Morbidity and Mortality Weekly Report . The increases come, surprisingly, despite improved air quality throughout most of the country and widespread decreases in smoking.

Free asthma screenings will be offered in May around the country, including several in Los Angeles and Orange counties, according to the American College of Allergy, Asthma and Immunology . Allergists encourage anyone who has breathing problems such as coughing, wheezing or shortness of breath or uncontrolled asthma to attend a screening. This year, the Nationwide Asthma Screening Program includes a special initiative to identify people who have difficulty breathing during or immediately after exercise and may have a condition called exercise-induced bronchoconstriction.

Children raised on farms don't suffer from asthma as much as their city- and suburb-dwelling counterparts, according to a paper published online Wednesday in the New England Journal of Medicine. But it's not necessarily because of the fresh air, full sun and hard work, researchers say -- it's because of the germs. Scientists had known that many of the things associated with farm life -- unpasteurized milk, exposure to animals such as cows and pigs, and hay -- helped kids grow up with stronger constitutions, perhaps because they were being exposed to harmless, even beneficial, bacteria along the way. To test this hypothesis, the researchers analyzed samples of house dust to look at the microbes within.

The Food and Drug Administration on Thursday issued its strongest warning against the use of a drug prescribed off-label to prevent preterm labor, saying it appears to be ineffective at delaying premature births and poses serious health risks for pregnant woman who take it for longer than 72 hours. The warning comes less than two weeks after the FDA approved a new drug , called Makena, to reduce the risk of premature delivery. One in eight babies born in the U.S. each year -- 543,000 -- is born prematurely, says the March of Dimes . Terbutaline , commercially marketed as Brethine and Bricanyl, is a drug approved for the treatment of asthma and chronic obstructive pulmonary disorder, sometimes called emphysema.

Families who eat dinner at home together tend to have more nourishing meals, but there may be other health benefits as well. A study finds that having quality family interactions at mealtime was linked with better overall health for children with asthma. Family meals were recorded via video for 200 families with children age 5 to 12 who had persistent asthma. Researchers noted how the families spent their time together and found most time was spent either in activity (talking on the phone, watching television)

Air filters will be installed in more than 40 Wilmington-area schools in an effort to alleviate asthma linked to pollution from the Port of Los Angeles, air quality officials announced Tuesday. The $5.4-million contract is part of a landmark 2008 settlement between environmental groups and the city of L.A., after community opposition threatened to halt a $274-million terminal expansion at the port. The settlement, negotiated by the Natural Resources Defense Council, Coalition for a Safe Environment and other groups, led to the creation last October of a $50-million trust fund for Wilmington and San Pedro to offset the effects of pollution from the movement of goods.

Even as a high-profile panel of experts recently disputed the conventional wisdom that Americans don't get enough vitamin D -- and that vitamin D deficiencies create greater risk of disease -- new research shows that newborns with low levels of vitamin D have higher rates of respiratory infection and wheezing than infants born with more vitamin D in their systems. There was no correlation, however, between low vitamin D levels and asthma. The study, published Monday in the journal Pediatrics, expanded on earlier work by Dr. Carlos Camargo of the Massachusetts General Hospital in Boston that had shown that babies born to mothers who took vitamin D supplements were less likely to develop wheezing during childhood.